| Objective: To evaluate the role of proton magnetic resonance spectroscopy (1H-MRS) for characterization of brain tumors and to ascertain its reliability in grading of gliomas.Materials and Methods: 1H-MRS was performed in 40 cases with pathologically-proven brain tumors, including 15 low-grade astrocytomas (grade I ~II), 5 high-grade astrocytomas (grade III~IV), 13 meningiomas and 7 metastasis. Single-voxel spectra were acquired using a point-resolved spectroscopic (PRESS) pulse sequence as part of the Probe. The ratios of NAA/Cr, Cho/Cr and NAA/Cho were compared with the histologic type of the lesions. Corresponding spectra obtained from normal-appearing brain parenchyma in all cases were used as control group.Results: All tumor spectra, characterized by dropping of NAA/Cr and NAA/Cho ratios and elevating of Cho/NAA ratio, were remarkably different from spectra from normal brain tissue (P<0.05) . Spectra obtained from different tumors exhibited differences from each other. NAA/Cr and NAA/Cho ratios were significantly lower and Cho/Cr ratio was significantly higher in meningiomas than in metastasis, low-grade and high-grade astrocytomas (P<0.05). High-grade astrocytomas were differentiated from low-grade ones by lower NAA/Cr and NAA/Cho ratios (P<0.05). The spectra from metastasis were similar to that from high-grade astrocytomas.The presence of lactate is not a reliable indicator of malignancy. Conclusions: 1H-MRS can provide information about tissue metablism and elevate the level of medical image in the histologic classification and pathologic grading of brain rumors.
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